And I'm David Greene. Good morning. Let's catch up on the Senate's fight over Obamacare. A handful of Republican senators say they support a plan to deny funding to the Affordable Care Act. They want to attach that to a larger measure designed to keep the rest of the government running and avoid a partial shutdown at the end of the month.

The House has already passed that measure, but it's considered very unlikely to pass the Senate. Even if it did, Obamacare would be hard to disable, as NPR's David Welna reports.

DAVID WELNA, BYLINE: The measure that would keep the government's lights on after next Monday is known as a continuing resolution, and by law it has to start in the House. Still, it's Ted Cruz, a freshman Republican senator from Texas with strong Tea Party ties, who has been the most outspoken champion of the defunding of Obamacare that's in the House bill.

SENATOR TED CRUZ: If the House continuing resolution is passed into law, all funding for Obamacare - both discretionary and mandatory - would be cut off.

WELNA: That continuing resolution is ostensibly for temporary government funding. But Scott Lilly, who is a former staff director for the House Appropriations Committee Democrats, says anything else that's included in that resolution becomes the lasting law of the land.

SCOTT LILLY: And as long as it's passed in identical form by both houses and signed by the president, then you could do anything within the limits of the Constitution in a continuing resolution.

WELNA: But while the measure defunding Obamacare sailed through the House, it faces tough sledding in the Senate. Harry Reid leads that chamber's Democratic majority. Here he is yesterday speaking to reporters.

SENATOR HARRY REID: I want to be very, very clear again. The Senate will not pass any bill that defunds or delays Obamacare.

WELNA: Reid intends to strip out the language in the House bill defunding the health care law. To do that he would need 51 votes in a chamber where he has 54 senators in the majority.

Arizona Republican John McCain said yesterday the fix is in.

SENATOR JOHN MCCAIN: It will be a cold day in Gila Bend, Arizona when we defund Obamacare. In fact, it may be a snowstorm in Gila Bend, Arizona when that happens.

WELNA: Meanwhile, Texas Republican Cruz is paradoxically urging his GOP colleagues to filibuster the very House bill he strongly supports, with the aim of preventing the Democratic leader from amending that measure. But Senate Republican Leader Mitch McConnell declared on the Senate floor yesterday he would not be joining Cruz.

SENATOR MITCH MCCONNELL: I just don't happen to think filibustering a bill that defunds Obamacare is the best route to defunding Obamacare.

WELNA: The reason, McConnell said later, is simple.

MCCONNELL: We'd all be hard-pressed to explain why we were opposed to a bill we were in favor of.

WELNA: Cruz, for his part, held the Senate floor for hours, where he castigated his colleagues.

CRUZ: When we go out and tell the American people it can't be done, there's nothing that can be done to stop Obamacare, what we're saying really is we're not willing to do it.

WELNA: There still is a very real possibility that Congress won't be able to agree on a stopgap spending measure by Monday and parts of the federal government would have to be shut down. But as Oklahoma Republican Senator Tom Coburn explained at a town hall meeting last month in Muskogee, all but about 15 percent of funding for Obamacare is mandatory.

SENATOR TOM COBURN: I don't care whether we shut down the government or don't shut down the government, Obamacare, 85 percent of it is going to get implemented. And if we shut down the government, all the president has to do - and he's already done it - declared all the employees associated with Obamacare as essential. So it means everything with Obamacare is going to happen, whether we shut it down or not.

WELNA: Not if Ted Cruz can help it. Here he is yesterday on the Senate floor.

CRUZ: I intend to speak in support of defunding Obamacare until I am no longer able to stand.

WELNA: And yet even Cruz has acknowledged he does not have the votes to make that happen.